Talc antiblock compositions and method of preparation

ABSTRACT

The present invention relates to a product, a process for its preparation and the use of such in plastic film production. More specifically, the present invention relates to an antiblock talc, a process for the preparation of such and its use as an additive in the production of polyolefin film. 
     Polyolefin films produced according to the process of the present invention are useful in a broad range of packaging and film covering applications.

This is a divisional application of U.S. Ser. No. 09/343,825, filed Jun.30, 1999, now U.S. Pat. No. 6,593,400.

FIELD OF THE INVENTION

The present invention relates to a product, a process for itspreparation and the use of such in plastic film production. Morespecifically, the present invention relates to an antiblock talc, aprocess for the preparation of such and its use as an additive in theproduction of polyolefin film.

Polyolefin films produced according to the process of the presentinvention are useful in a broad range of packaging and film coveringapplications.

BACKGROUND OF THE INVENTION

Polyolefin films are used extensively for packaging and in film coveringapplications. The use of polyolefin films continues to increase as newmarket opportunities become available in areas where paper wastraditionally used. The versatility of the film provides potentiallyinfinite growth prospects for the product in the future. However, thereis an inherent short coming in the use of plastic films that may retardits market acceptance and growth, it sticks. When plastic film isproduced or used in various applications, there is a tendency forcontacting layers of the film to stick together or “block”, makingseparation of the film, opening of bags made from the film, or findingthe end of the film on plastic rolls difficult. The present inventionrelates to polyolefin resin compositions that are specifically designedto have satisfactory antiblocking capability.

Antiblock agents are materials that are added to polyolefin resins toroughen their surface and thereby prevent layers of the plastic filmfrom sticking, hence the term, “antiblocking agent” is applied to suchmaterials. Although, inorganic minerals, such as, for example,diatomaceous earth, synthetic silica and talc are known to reduceblocking when added to polyolefin film resin compositions, each has bothadvantages and critical disadvantages.

One comparative advantage of diatomaceous earth is that it is known tobe a moderately effective antiblocking agent, when used as anantiblocking agent. However, it is also known that diatomaceous earthadversely affects the film's physical properties, such as film clarity,film haze, and is very abrasive and moderately expensive and may pose aserious health threat. Synthetic silicates are known to be effective asan antiblock, however a significant disadvantage of silica is that it isvery expensive. Talc, on the other hand, has found increasing use as aneffective antiblock agent over diatomaceous earth and synthetic silicabecause of a significant cost advantage over both. However, one majordisadvantage when talc is added to polyolefin film resins, is that itaggressively adsorbs other film additives, such as antioxidants, slipagents and processing aid. The absence, or reduced level of theseadditives in polyolefin resin compositions during production, routinelycause processing problems and raise serious film quality concerns.

For example, antioxidants are added to improve film stability, slipagents are present in the resin to improve film converting, whileprocessing aids are employed to improve film quality, and to providelubrication during film extrusion by eliminating melt fracture. Meltfracture is a measure of film surface uniformity, appearance andstrength. Of the three additives mentioned here, processing aids aremost adversely affected by the presence of antiblock agents. Although itis well known that all antiblock agents adsorb processing aids, talcantiblock agents adsorb greater levels of processing aids than eitherdiatomaceous earth or synthetic silica antiblocks. Consequently, whenresin compositions are produced having additives that include antiblocktalc, it is necessary to increase the dosage of processing aids. Theincreased dosage adversely effects the over all production economics ofthe plastic film.

Therefore, what is needed is a new generation of talc antiblock agentsthat adsorb less process aids than either synthetic silica ordiatomaceous earth.

RELATED ART

U.S. Pat. No. 5,401,482, discloses a method for the manufacture of atalc substance consisting of particles having a sheet structure, eachparticle having an internal crystalline structure and at least onehydrophilic surface, the method comprising heating talc particles to atemperature below 900 degrees Centigrade under conditions such as toavoid conversion of the talc into enstatite and in order to effect asurface modification consisting of substituting inert siloxane groups byactive silanols.

U.S. Pat. No. 5,229,094 discloses a talc substance consisting ofparticles having a sheet structure, each particle comprising internalhydrophobic sheets, having the crystalline structure of talc within eachunit and bonded together by cohesion forces typical of talc (Van derWaals forces), the talc substance being characterized in that eachparticle has at least one hydrophilic surface sheet.

SUMMARY OF THE INVENTION

A product and a method for producing an antiblock agent comprisingsurface treating an inorganic mineral with a functionalized siloxanepolymer or a polyether polymer or functionalized polyether polymer orcarbon based polymer. When inorganic minerals are coated with afunctionalized siloxane polymer or a polyether polymer or afunctionalized polyether polymer or carbon based polymer andsubsequently used as an additive in the production of polyolefin film,the adsorption of other resin additives is substantially reduced.

Polyolefin films produced according to the process of the presentinvention are useful in a broad range of packaging and film coveringapplications.

DETAIL DESCRIPTION OF THE INVENTION

In one aspect the present invention embodies surface treating talc withcertain types of silanes or siloxane polymers. The treated talc inhibitsthe adsorption of plastic film additives onto the talc. Surface treatingmeans coating, partially coating, or using an effective amount toinhibit the adsorption of other additives. The invention embodies ofcoating any talc material with a functionalized polydialkyl, preferablypolydimethylsiloxane, having the structural formula:[Si(CH₃)(R)—O—Si(CH₃)(R)—O]_(n)where n is the number of repeating units (molecular weight), CH₃ is amethyl group, Si is silicon, O is oxygen, and R is a functionalizedalkyl group. The alkyl group may, without limitation, be functionalizedwith carboxylate, amine, amide, thiol, sulfate, phosphate, and the like.

Siloxane polymers that are useful in the present invention may beselected from the group consisting of functionalized alkylpolydimethylsiloxane (carboxylate, amine, amide, thiol, sulfate,phosphate) wherein carboxylate is preferred, Bis-(12-hydroxystearate)terminated polydimethylsiloxane (Aldrich Chemical Co.—1001 West SaintPaul Avenue, Milwaukee, Wis. 53233), andPoly(Dimethylsiloxane)-Graft-Polyacrylates (Aldrich). There is nolimitation on the method used to produce the siloxane polymers. Thesiloxane polymers of the present invention may be manufactured by ionicpolymerization or radical polymerization and the like, or any otherprocess known to produce siloxane polymers.

The molecular weight range of the siloxane polymer is from about 1000 toabout 1,000,000 atomic mass units (a.m.u.), preferably ranges from about1000 to about 100,000 a.m.u. The molecular weight can be determined bygel permeation chromatography (GPC).

Silanes that are useful in the present invention have the structuralformula SiR₄, where Si is silicon, R can be any group capable of forminga covalent bond with silicon (e.g., an alkyl group, an alkoxy group, afunctionalized alkyl group, and a functionalized alkoxy group, and anycombination thereof). The following silanes are useful in the presentinvention: Octyltriethoxysilane (OSi Silquest® A-137 silane), Triaminofunctional silane (OSi Silquest® A-1130 silane),Bis-(gamma-trmethoxysilylpropyl) amine (OSi Silquest® A-1170 silane),all of which are commercially available from OSi.

In another aspect, the present invention consists of coating talc withpolyethers and functionalized polyethers to reduce film additiveadsorption onto the talc. The general structural formula is:H—(OCHR(CH₂)_(x)CHR₁)_(n)—OHwhere n is the number of repeating units (molecular weight), x is zeroor an integer, R is an alkyl group, O is oxygen, C is carbon, H ishydrogen, and R₁ is a functional group which may be, without limitation,an alkyl carboxylate, an alkyl amine, an alkyl amide, an alkyl thiol, analkyl sulfate, an alkyl sulfonate, an alkyl phosphate or an alkylphosphonate and the like.

Polyethers and functionalized polyethers that are useful for the surfacetreatment of talc may be selected from the group consisting ofpoly(ethylene glycol), poly (ethylene glycol) Bis-(carboxymethyl) ether,poly (ethylene glycol) dimethyl ether, poly (ethylene glycol-400)distearate, and the like, and functionalized polyethers (alkylcarboxylate, alkyl amine, alkyl amide, alkyl sulfate, alkyl thiol, alkylsulfonate, alkyl phosphate, alkyl phosphonate) wherein alkyl carboxylatefunctionality is preferred. There is no limitation on the method used toproduce the polyethers and functionalized polyether polymers. Thepolyethers and functionalized polyethers of the present invention may bemanufactured by ionic polymerization or radical polymerization and thelike, or by any other process known to produce polyethers andfunctionalized polyethers.

The molecular weight range of the polyethers and functionalizedpolyethers is from about 1000 to about 10,000,000 a.m.u., with apreferred range of from about 10,000 to about 1,000,000 a.m.u. Themolecular weight can be determined by GPC.

In a further aspect the present invention pertains to the use of carbonbased polymer coatings for surface treating the talc in order to lowerthe level of additive adsorption. Also included in the definition ofcarbon based polymers are maleic acid/olefin co-polymers having thegeneral formula:

where n denotes molecular weight and x and y represent the ratio of eachmonomeric unit in the polymer. Carbon based polymers that are useful forthe surface treatment of talc may be selected from the group consistingof functionalized polyolefins: maleic acid/olefin copolymer, maleicacid/styrene copolymer, wherein maleic acid/styrene copolymer ispreferred. Also included in the carbon-based polymers group are mineraloils of any boiling point and paraffin waxes of any melting point. Thex/y ratio can range from about 100:1 to about 1:100, wherein thepreferred range is from about 10:1 to about 1:10. C is carbon, O isoxygen, H is hydrogen and R is a functional group. R may be any groupthat can form a bond with carbon. This includes, without limitation,alkyl carboxylates, alkyl amines, alkyl amides, alkyl thiols, alkylsulfates, alkyl sulfonates, alkyl phosphates, and alkyl phosphonates andthe like.

The molecular weight of the carbon based polymer may range from about100 to about 10,000,000 a.m.u., with a preferred range of from about 200to about 2,000,000 a.m.u.

Any inorganic mineral, such as, talc, calcium carbonate, precipitatedcalcium carbonate, clay or silica, that is receptive to surfacetreatment may be coated with the polymers described herein. However,talc is the preferred inorganic mineral. Talcs that are particularlyuseful are those that are receptive to both surface treatment and thatare capable of subsequent use in polyolefin film production. Anexemplary, but nonlimiting talc, would typically have an empiricalformula of Mg₃Si₄O₁₀(OH)₂, and a specific gravity of from about 2.6 toabout 2.8. The preferred talc, without other limitations, could have anaverage particle size of from about 0.1 microns to about 10 microns,wherein the preferred average particle size is from about 0.5 microns toabout 5 microns. The talc may be coated with from about 0.01 weightpercent to about 10 percent of the polymers described herein, whereinthe preferred treatment level for coating is from about 0.25 weightpercent to 2 weight percent, based on the weight of the polymer.

All of the polymer coatings described herein may be applied to talc byany convenient dry powder mixing operation. The temperature at which thecoating is applied to the talc, ranges from about 0 zero degreesCentigrade (C) to about 500 degrees C., preferably from about 30 degreesC. to about 200 degrees C., and more preferably, from about 60 degreesC. to about 80 degrees C. The application temperature should be adjustedto higher levels if the specific coating requires melting. Once the talcis coated, an antiblock talc is produced that may be used, by thoseskilled in the art, just as any other commercially available antiblock.For example, but without limitations, the coated antiblock talc may beadded to the film extruder or added as an already compounded masterbatchto the extruder. A compounded masterbatch means the resin and theantiblock are pre-mixed in a compounder before being added to the filmextruder.

Polyolefins considered suitable for the present invention may be anypolyolefin, which can be clear, crystalline, and capable of forming aself-supported film. Non-limiting examples include crystallinehomopolymers of α-olefin with carbon numbers ranging from 2 to 12 or ablend of two or more crystalline copolymers or ethylene-vinylacetatecopolymers with other resins. Also, the polyolefin resin can be ahigh-density polyethylene, low density polyethylene, linear low-densitypolyethylene, polypropylene, ethylene-propylene copolymers,poly-1-butene, ethylene-vinyl acetate copolymers, etc., and low andmedium-density polyethylenes. Additional examples are represented byrandom or block copolymers of polyethylene, polypropylenepoly-r-methylpentene-1, and ethylene-propylene, andethylene-propylene-hexane copolymers. Among them, copolymers of ethyleneand propylene and those containing 1 or 2 selected from butene-1,hexane-1,4-methylpentene-1, and octene-1 (the so-called LLDPE) areparticularly suitable.

The method of producing polyolefin resin used in the present inventionis not limited. For example, it can be manufactured by ionicpolymerization or radical polymerization. Examples of polyolefin resinsobtained by ionic polymerization include homopolymers such aspolyethylene, polypropylene, polybutene-2, and poly-4-methylpentene andethylene copolymers obtained by copolymerizing ethylene and α-olefin,α-olefins having from 3 to 18 carbon atoms such as propylene,butene-1,4-methylpentene-1, hexene-1, octene-1, decene-1, andoctadecene-1 are used as α-olefins. These α-olefins can be usedindividually or as two or more types. Other examples include propylenecopolymers such as copolymers of propylene and butene-1. Examples ofpolyolefin resins obtained by radical polymerization include ethylenealone or ethylene copolymers obtained by copolymerizing ethylene andradical polymerizable monomers. Examples of radical polymerizablemonomers include unsaturated carboxylic acids such as acrylic acid,methacrylic acid and maleic acid esters and acid anhydrides thereof, andvinyl esters such as vinyl acetate. Concrete examples of esters ofunsaturated carboxylic acids include ethyl acrylate, methyl methacrylateand glycidyl methacrylate. These radical polymerizable monomers can beused individually or as two or more types.

A typical embodiment of the present invention could include:

From To about about 0.1%–1.0% talc antiblock 0.02%–0.5%  process aid0.05%–0.25% slip agent 0.01%–0.5%  antioxidant 0.01%–0.25% scavenger0.1%–5.0% siloxane, silane, polyether, carbon based polymer 99.7%–92.5%polyolefin resinA typical preferred embodiment of the present invention includes:

 0.5% talc antiblock  0.15% process aid  0.12% slip agent  0.03%antioxidant  0.05% scavenger  0.10% antioxidant  2.50% siloxane, silane,polyether, carbon based polymer 96.55% polyolefin resinAll percentages are based on total weight percent.

TEST METHODS AND PROCEDURES Equipment

-   1. Extruders. The following extruders were used to measure the    effect of antiblocks on process aid (PA) performance.    -   a. Brabender Single Screw Tape Die Extruder    -   b. ZSK co-rotating low intensity twin screw extruder    -   c. Lestritz low intensity counter-rotating twin screw extruder    -   d. Welex Extruder-   2. Henshal Mixer. Used for mixing the siloxane, or silane, or    polyether, or carbon based polymer and antiblock compounds.-   3. Killion Blown Film Line. This is a 1^(1/4) inch extruder with a    L/D ratio of 30:1 and 2^(1/2) inch die with a 12 mm die gap. The    temperature profile of the extruder and the blown film line were    177° C., 93° C., 193° C., 204° C., 204° C., 204° C., 204° C., 204°    C., 204° C., and 204° C. with a melt temperature of 200–208° C.    Output was about 9 lbs/hr. with a sheer rate of 500 sec⁻¹. Die    pressure and melt fracture reduction were monitored every 15 minutes    for two hours.

Definition of Terms

-   -   Extrusion—fundamental processing operation in which a material        is forced through a metal forming die, followed by cooling or        chemical hardening (see Hawley's Condensed Chemical Dictionary,        12^(th) Edition 1993, page 505).    -   Die—a device having a specific shape or design in which it        imparts to plastic by passing the material through it        (extrusion). Die extruders are used to measure the effect of        anti-blocks on process aid (PA) performance.    -   Tape Die Extrusion—extrusion procedure for measuring process aid        demand based on the amount of process aid required to reduce die        pressure and eliminate melt fracture.    -   Antiblock—materials that roughen the surface of plastic films to        reduce their tendency to stick together. These materials may        include synthetic silica, diatomaceous earth (DE), and talc.    -   Clarity Antiblock—a type of antiblock that is added when        compounding chemicals, to reduce opacity and to improve the        clarity of the polymer film.    -   Process Aid (PA)—provides lubrication or slip at the die during        film extrusion, which improves film quality by elimination of        melt fracture. Process aids are evaluated on pressure reduction        (less PA absorbed) and elimination of melt fracture (percent        melt fracture).    -   Die Pressure—Pressure at the die. Die pressure reduction is how        well the process aid is performing, meaning that the process aid        is not absorbed by the talc and hence, is available to reduce        die pressure.    -   Melt Fracture—a measure of film surface uniformity. The        objective is complete elimination of melt fracture. Melt        fracture is monitored as 1 a function of time at a given PA        dosage and measured in a rate-conditioning test.    -   Rate of Conditioning—Technique used by film manufacturers to        determine process aid (PA) performance and to determine the        effect of a given antiblock on PA effectiveness. This is done        using tape die extrusion and monitoring die pressure and percent        melt fracture over a period of time.    -   ABT-G—an ABT 2500® talc coated with an amine functionalized        siloxane (Genese Polymers, GP-4).    -   Functional Groups—The arrangements of atoms and groups of atoms        that occur repeatedly in an organic substance.    -   Blown Film Test—Type of extrusion that after the polymer        compounded is formed to its desired thickness by air being blown        through a cylindrical die.    -   Antioxidant—An organic compound added to plastics to retard        oxidation, deterioration, rancidity, and gum formation (see        Hawley's Condensed Chemical Dictionary, 12^(th) Edition 1993,        page 90).    -   Feldspar—General name for a group of sodium, potassium, calcium,        and barium aluminum silicates (see Hawley's Condensed Chemical        Dictionary, 12^(th) Edition 1993, page 509).    -   Diatomaceous earth (DE)—Soft, bulky, solid material (88% silica)        composed of small prehistoric aquatic plants related to algae        (diatoms). Absorbs 1.5 to 4 times its weight of water, also has        high oil absorption capacity (see Hawley's Condensed Chemical        Dictionary, 12^(th) Edition 1993, page 365).    -   Paraffin (alkane)—a class of aliphatic hydrocarbons        characterized by a straight or branched carbon chain        (C_(n)H_(2n+2)) (see Hawley's Condensed Chemical Dictionary,        12^(th) Edition 1993, page 871).

EXAMPLES

The following examples are intended to be illustrative of the presentinvention and are not proffered, in any manner whatsoever, to limit thescope of the present invention which is more specifically defined by theappended claims.

Section I

Investigation of Talc Coatings to Reduce Process Aid (PA) Demand ofAnti-blocks

In Example 1 and Example 2, the antiblock is compounded with a linearlow-density polyethylene (PE) in a ZSK co-rotating low intensity twinscrew extruder at 30 percent loading levels. In a separate batch processthe process aid is compounded with the PE at a 10 percent loading level.Process aid dosage was varied from zero parts per million to 1400 ppm in200 ppm increments. The samples were extruded at a constant rate (20g/min) for one hour, at each increment, with die pressure and tape meltfracture being monitored throughout. VITON® Free-Flow SAX 7431 (GenesePolymers) process aid was used in Example 1 and replaced with Dynamar™FX-5920 (Dynamar Products—3M Center, St. Paul, Minn. 55144) process aidin Example 2.

The effect of anti-block type on PA performance is determined using a ¾″Brabender single screw extruder fitted with a 1″×0.020″ ribbon tape die.The extruder was run with a sheer rate of 400–500 sec.⁻¹ and with anoutput of 20 grams per minute. PA performance was monitored by diepressure and by percent melt fracture of the extruded PE tape over aone-hour time period.

Example 1 Process Aid Demand for Various Antiblocks

ABT® 2500 talc, ABT® 2500 talc treated with an amine functionalizedsiloxane (ABT-G), B4 (Viton Products—Viton Business Center, P.O. Box306, Elkton, Md. 21922) clarity antiblock, B4 treated with an aminefunctionalized siloxane, Celite 238 D.E. (Celite Products—Solon, Ohio),synthetic silica, and MICROBLOC® talc. The treated antiblocks areprepared by dry coating in a Henshal mixer for ten minutes, at 70° C.,with a siloxane polymer, at a coating level of one percent by dry weightof talc. The coating consisted of an amine functionalized siloxane(Genese Polymers—GP-4).

In addition to analyzing the three talc samples described above, aclarity antiblock consisting of 50 percent by volume MP 10–52 and 50percent by volume Feldspar, a GP-4 treated clarity antiblock, ABT 2500®talc, MICROBLOC® talc, diatomaceous earth (Celite Superfloss 238) andsynthetic silica (Crosfield 705—Crosfield Products—101 Ingalls Avenue,Joliet, Ill. 60435) were also examined.

TABLE 1 VITON ® FLUOROELASTOMER PROCESS AID DOSAGE Process AidAnti-Block (parts per million) Percent Melt Fracture ABT ® 2500 talc1200 40 ABT-G siloxane coated talc 400 10 B4 clarity antiblock 1000 25B4 siloxane coated 400 15 Celite 238 D.E. 800 40 Synthetic Silica^(a)600 2 MICROBLOC ® talc 1000 20 ^(a)2000 parts per million syntheticsilica

Lower process aid dosages were required to reduce melt fracture when thetalc and clarity antiblocks were treated with a siloxane coating.

Example 2 Talc and Synthetic Silica as Antiblocks

In this example, the process aid used in Example 1 was replaced Dynamar™FX-5920 process aid. ABT 2500® talc (uncoated and coated with asiloxane) was compared with a synthetic silica and a commerciallyavailable antiblock for process aid demand. Table 2 shows the amount ofprocess aid required to reduce melt fracture.

TABLE 2 DYNAMAR ™ FLUOROELASTOMER PROCESS AID DOSAGE Process AidAnti-Block (parts per million) Percent Melt Fracture ABT ® 2500 talc1200 50 ABT-G siloxane coated talc 1000 20 Synthetic Silica^(a) 1200 80MICROBLOC ® talc 1200 65 ^(a)2000 parts per million synthetic silica

The siloxane coated talc required lower amounts of process aid to reducemelt fracture than did the other antiblocks.

Section II

Antiblock Coatings and Their Effect on Process Aid Performance

In Example 3, melt fracture and die pressure data of ABT® 2500 talc,ABT-G siloxane coated talc, and diatomaceous earth (DE) were compared.In Example 4, commercially available talc antiblocks were evaluated forprocess aid performance and compared with those in Example 3. Examples 5through Example 7 investigate alternative coatings for an improvedantiblock.

The antiblocks were compounded with blends containing polyethyleneresin, 5,000 ppm antiblock, 1,000 ppm VITON® Free Flow SAX—7431 PA,1,200 ppm Croda ER erucamide slip agent, 300 ppm Irganox® 1010antioxidant, 500 ppm J. T. Baker zinc stearate scavenger, and 1,000 ppmIrgafos® 168 antioxidant were compounded on the Lestritz low intensitycounter-rotating twin screw extruder. Extruder conditions consisted oftemperature zones of 165° C., 175° C., 190° C., 200, and 204° C. A screwspeed at 150 rpm with one port and one hopper. The extender screws were34 mm in diameter with a L/D ratio of 22:1.

Example 3 Melt Fracture and Die Pressure Performance of Antiblocks

Die pressure and percent melt fracture were determined for ABT® 2500talc, ABT-G siloxane coated talc, and DE antiblocks, using tape dieextrusions. Percent melt fracture and die pressure data for theseantiblocks throughout a one-hour tape extrusion are listed below.

TABLE 3 RATE OF CONDITIONING Benchmark Antiblocks ABT-G ABT ® 2500siloxane Diatomaceous talc coated talc Earth Die Die Die % Melt Pressure% Melt Pressure % Melt Pressure Time (min) Fracture (psi) Fracture (psi)Fracture (psi)  0 100 3110 10 3100 100 3100 10 100 3100 100 3100 1003040 20 100 3100 100 3100 55 2740 30 95 3100 85 2990 20 2640 40 90 307060 2830 10 2540 50 80 2870 50 2790 0 2480 60 65 2880 35 2760

A decrease in melt fracture of 30 percentage points and a die pressurereduction of 120 psi was seen when ABT® 2500 talc was treated with anamine functionalized siloxane (ABT-G).

Example 4 Commercial Talc Antiblocks

In this example, commercially available MICROBLOC® talc, POLYBLOC™ talc,and MICROTUFF® AG 101 talc antiblocks were compared with the antiblocksused in Example 3. Measurements were taken throughout a one-hour tapeextrusion. Percent melt fracture is found in Table 4 and die pressuredata in Table 5.

TABLE 4 RATE OF CONDITIONING/COMMERCIAL TALCS Percent Melt FractureABT-G ABT ® siloxane Time 2500 coated MICROBLOC ® POLYBLOC ™ MICROTUFF ®(min) talc talc D.E. Talc Talc AG 101 Talc 0 100 100 100 100 100 100 10100 100 100 100 100 100 20 100 100 55 96 95 100 30 95 85 20 95 85 85 4090 60 10 75 75 65 50 80 50 0 50 55 55 60 65 35 40 40 45 MICROBLOC ®,POLYBLOC ™, and MICROTUFF ® are trademarks of and are commerciallyavailable through Minerals Technologies Inc. - The Chrysler Building,405 Lexington Avenue, New York, New York 10174.

The siloxane coated talc (ABT-G) had a lower percentage melt fracturethan the commercially available talc antiblocks.

Table 5 RATE OF CONDITIONING/COMMERCIAL TALCS Die Pressure (psi) ABT-GABT ® siloxane Time 2500 coated MICROBLOC ® POLYBLOC ™ MICROTUFF ® (min)talc talc D.E. Talc Talc AG 101 Talc 0 3110 3100 3100 3110 3140 3120 103100 3100 3040 3110 3130 3120 20 3100 3100 2740 3100 3130 3120 30 31002990 2640 3090 3030 3020 40 3070 2830 2540 2930 2950 2950 50 2970 27902480 2860 2840 2850 60 2880 2760 2790 2780 2790

The siloxane coated talc (ABT-G) had lower die pressure than thecommercially available talc antiblocks.

Example 5 Siloxane Coated Talc Antiblocks

ABT 2500® talc in addition to being coated with the amine functionalsilicone fluid (ABT-G)/(Genese Polymers, GP-4), was coated with an aminomodified propyltrimethoxy silane (OSI, Silquest® A-1130 silane), and abis-(trimethoxysilylpropyl) amine (OSI, Silquest® A-1170 silane). Tapedie extrusions were used to determine melt fracture and die pressure.

Tape die extrusion results are listed in Table 6 and Table 7.

TABLE 6 RATE OF CONDITIONING Percent Melt Fracture SIL- SIL- QUEST ®QUEST ® ABT ® ABT-G A-1130 A-1170 Time 2500 coated coated coatedPolyacrylate (min) talc talc D.E. talc talc coated talc 0 100 100 100100 100 100 10 100 100 100 100 100 100 20 100 100 55 98 95 95 30 95 8520 95 85 90 40 90 60 10 85 60 65 50 80 50 0 75 45 45 60 65 35 65 30 35

SILQUEST® A-1170 and the polyacrylate coated products show lower meltfracture than the uncoated talc and performs similarly to siloxanecoated (ABT-G) talcs.

TABLE 7 RATE OF CONDITIONING Die Pressure (psi) Time ABT ® ABT-SILQUEST ® SILQUEST ® Poly- (min) 2500 G D.E. A-1130 A-1170 acrylate 03110 3100 3100 3110 3140 3110 10 3100 3100 3040 3110 3130 3100 20 31003100 2740 3110 3120 3100 30 3100 2990 2640 3080 2980 3080 40 3070 28302540 3060 2800 2940 50 2970 2790 2480 2970 2770 2790 60 2880 2760 28702710 2750

ABT® 2500 talc coated with SILQUEST® A-1170 and the polyacrylate showreduced die pressures when compared with the uncoated ABT® 2500 talc.

Example 6 Polyether Coated Talc Antiblocks

This example shows the effect of polyethers as coatings for low PA talcantiblocks. ABT® 2500 talc was coated with polyethylene glycol (PEG), aPEG product functionalized with polar carboxylate groups, and a PEGproduct functionalized with less polar stearate groups. Melt fracturedata is found in Table 8 and die pressure results are found in Table 9.

TABLE 8 RATE OF CONDITIONING/POLYETHER COATINGS Percent Melt FracturePolyethylene ABT ® ABT-G Glycol PEG PEG Time 2500 siloxane (PEG) 200Carboxy Distearate (min) talc coated talc D.E. coated talc coated talccoated talc 0 100 100 100 100 100 100 10 100 100 100 100 100 100 20 100100 55 100 100 95 30 95 85 20 95 95 70 40 90 60 10 75 75 40 50 80 50 055 55 35 60 65 35 45 30 25

All three ether coated talcs had lower melt fractures than the uncoatedABT® 2500 talc.

TABLE 9 RATE OF CONDITIONING/POLYETHER COATING Die Pressure (psi)Polyethylene ABT ® ABT-G Glycol PEG Time 2500 siloxane (PEG) 200 CarboxyPEG (min) talc coated talc D.E. coated talc coated talc Distearate 03110 3100 3100 3100 3120 3140 10 3100 3100 3040 3100 3110 3100 20 31003100 2740 3090 3080 3090 30 3100 2990 2640 3070 3030 2930 40 3070 28302540 2930 2840 2820 50 2970 2790 2480 2840 2770 2760 60 2880 2760 27502740 2670

All three ether coated talcs had lower die pressures than the uncoatedtalc.

Example 7 Carbon Based Polymer Coated Talc Antiblocks

Functionalized polyolefins and paraffins were examined for melt fractureand die pressure with respect to PA demand. The polyolefins included amaleic acid/olefin copolymer and a maleic acid/styrene copolymer. A lowmolecular weight paraffin (mineral oil) and a high molecular weightparaffin (paraffin wax) were also evaluated as talc coating. Themolecular weight of the paraffin is from about 80 to about 1400 a.m.u.,wherein the preferred molecular weight is from about 200 to about 600a.m.u. Melt fracture results are in Table 10 and die pressure results inTable 11.

TABLE 10 RATE OF CONDITIONING Percent Melt Fracture ABT ® Time 2500Maleic- Maleic- Mineral Paraffin (min) Talc ABT-G D.E. co-olefin styreneOil Wax 0 100 100 100 100 100 100 100 10 100 100 100 100 100 100 100 20100 100 55 100 100 100 90 30 95 85 20 90 90 90 60 40 90 60 10 40 75 6535 50 80 50 0 35 40 50 20 60 65 35 30 20 40 15

All four of the talc samples coated with a carbon-based polymer hadlower melt fracture than the uncoated ABT® 2500 talc. Paraffin waxshowed a melt fracture of 15 percent after one hour.

TABLE 11 RATE OF CONDITIONING Die Pressure (psi) ABT ® Time 2500 Maleic-Maleic- Mineral Paraffin (min) Talc ABT-G D.E. co-olefin styrene Oil Wax0 3110 3100 3100 3100 3080 3110 3120 10 3100 3100 3040 3100 3080 31003100 20 3100 3100 2740 3100 3070 3080 3010 30 3100 2990 2640 3030 30303020 2860 40 3070 2830 2540 2820 2900 2840 2760 50 2970 2790 2480 27202750 2780 2710 60 2880 2760 2700 2680 2750 2660

All of the carbon-based polymers had higher die pressure reductions thanthe uncoated ABT® 2500 talc.

1. A method of producing a polyolefin film comprising the steps of:surface treating an inorganic mineral selected from the group consistingof talc, calcium carbonate, precipitated calcium carbonate, clay, andsilica, with from about 0.1 percent to about 10 percent by weight of asilane to produce an antiblock agent; adding from about 0.1 percent toabout 1.0 percent by weight of the antiblock agent to a mixturecomprising about 92.5 to about 99.7 wt. % polyolefm resin; and extrudingthe mixture to form a polyolefin film.
 2. The method of claim 1 whereinthe inorganic mineral is talc.
 3. The method of claim 1 wherein theallaire is selected from the group consisting of octyltriethoxysilane,triamino functional silane, and Bis-(gamma-trimethoxysilylpropyl)amine.4. The method of claim 3 wherein the silane isBis-(gamma-trimethoxysilylpropyl)amine.
 5. The method of claim 3 whereinthe silane has a structural formula of SiR₄, where R is a functionalizedalkyl group or functionalized alkoxy group.
 6. The method of claim 2wherein the talc is surface treated with from about 0.1 percent to about2.0 percent, based on weight of the talc, of the silane.
 7. Acomposition comprising; about 92.5 to about 99.7 wt. % polyolefln resin;and from about 0.1 percent to about 1.0 percent by weight of anantiblock agent, wherein the antiblock agent comprising an inorganicmineral selected from the group consisting of talc, calcium carbonate,precipitated calcium carbonate, clay, and silica, the inorganic mineralbeing surface treated with from about 0.1 percent to about 10 percent,based on the weight of the inorganic mineral, of a silane.